This disclosure relates generally to a respiratory connector and an arrangement for connecting an inspiratory tube and an expiratory tube to a medical apparatus.
Conventional anesthesia machines and critical care ventilators are connected to a patient by means of inspiratory and expiratory tubes, which tubes can be side by side or as today more often coaxial. The reason to use coaxial tubes is that in that case expiration gas warms inspiration gas making breathing more pleasant for the patient. Usually an expiration air is flowing along an outer tube from the patient towards the machine and an inspiration air is flowing along an inner tube from the machine to the patient, whereby a warming of the inspiration air can be maximized and avoid cooling due to a lower room temperature. At machine end inspiratory and expiratory tubes need to be connected by a hospital personnel to the anesthesia machine or the ventilator preventing expiration and inspiration gases to be mixed. The aim is to use connectors, which are easy to use and safe. The working space in an operating room is limited and the personnel would like to minimize the amount of separate cables between patient and equipment.
While using coaxial inspiration and expiration tubes a connector is usually more complicated than when using tubes, which are side by side. One known solution is to direct an expiration flow coming from the patient along the outer coaxial tube to guide to a different route at the machine end of the connector than an inspiration air coming from the machine to the connector. This also means that the hospital personnel has to connect separately both the inspiration end of the connector to the machine and the expiration end of the connector and make sure the connections are tight enough to avoid leaking to the room air or from the room air to especially the inspiration air. This is too complicated and time consuming.
A newer approach while using coaxial breathing tubes is to avoid using different routes for inspiration and expiration gases inside the connector at the machine end, whereby the inspiration and expiration channels have a common coaxial machine end. This end will be connected to an adapter having coaxial channels for the inspiration and expiration air, but which channels inside the adapter guide these flows into different routes. The adapter is connected to a side of the machine and does not need to be detached, but instead can be used with many patients contrary to the connector which must be sterilized or which must be replaced with a new one. However, the adapter and the connector constitute a long device protruding from the side of the machine making it clumsy and vulnerable to users' pushes which may even cause a dangerous situation.
Also the more connections have to be made the more leaks and unintentional disconnections can appear. Especially a leak between inspiratory and expiratory line may be hazardous to the patient, because the patient may re-breath carbon dioxide. Further a disadvantage is that the user has to use both hands when connecting the connector at the machine end to the adapter, because the user has to hold in one of his/her hands the adapter and simultaneously in another hand the connector and to push the connector strongly towards the adapter to make both the inspiration and expiration channels' joints tight to avoid leakages. From mechanical perspective, the manufacturing of a reliable connector with two coaxial conical surfaces is very challenging. Especially with reusable parts the wearing of the sealing surfaces may cause these conical connectors not to be reliably sealing simultaneously. Also the molding tools wear and may cause similar risks. Typically, a ventilator can detect a leak in the breathing circuit if the gases are leaking out of the circuit. However, a leak between the inner and outer channel of coaxial tubing is much more difficult to detect, especially without separate patient gas monitoring.